Electrical appliance housing

ABSTRACT

An electrical appliance housing including a hard plastic housing body defining a switch-actuating aperture. The aperture is sealed with a soft plastic membrane. An actuating button is fastened to a hard plastic base that is bonded to the membrane.

FIELD OF THE INVENTION

This invention relates to an electrical appliance housing.

BACKGROUND OF THE INVENTION

Electric toothbrushes and other small electrical appliances such asshaving apparatus, kitchen appliances, and the like generally have awatertight housing in the interior in which there are often switches. Insome cases, it may be desired that the actuating energy for suchswitches be passed through the housing wall in a manner preventing theingress of water. In a typical arrangement the switch or other mechanism(e.g., a brake, coupling, valve, transmission, etc.) to be actuated liesbehind an aperture in the housing wall which is sealed by an elasticmembrane. To activate the appliance, the user presses (e.g., presseswith his or her finger) on the membrane, thereby actuating the switch orother mechanism underneath. The membrane is generally made of a softplastic material which is bonded to the hard plastic housing wall. Themembrane and the housing wall can be injection-molded by a two-componentinjection method.

As a visual and tactile indicator to the underlying switch, the membraneoften has a projection or some other three-dimensional structure on itsoutside surface. In cases in which the three-dimensional structure ismade of the same material as the membrane, the three-dimensionalstructure and the membrane generally have the same color, which canimpair recognition of the three-dimensional structure.

For this reason, some known appliances include a metal actuating buttoninserted in a hole passing through the membrane. However, such anarrangement can allow liquid (e.g., water) to pass through the hole intothe interior of the housing. Thus, water-tightness of the housing may nolonger be assured.

SUMMARY OF THE INVENTION

The invention relates to electrical appliance housings. In general, theelectrical appliance housings include an actuating button that isconnected to the membrane in such a way that water is prevented frompenetrating through the housing wall.

In one aspect of the invention, an actuating button is fastened to ahard plastic base that is bonded to a membrane. The hard plastic base ishermetically connected to the membrane such that substantially no watercan reach the interior of the housing. The plastic materials of the baseand the membrane can be compatible with each other to help ensure a firmbond between them. The actuating button can be made of any of variousmaterials without having to give consideration to a suitable materialpairing of the membrane and the actuating button to obtain a tightconnection to the membrane. The membrane can be injection-molded ontothe hard plastic base in a two-component injection-molding process.

In certain embodiments, the base which supports the actuating button isconnected by at least one elastic bar to the hard plastic housing body.In some embodiments, the elastic bar is constructed to exhibit materialhomogeneity with the housing body and/or the base, and is formed in oneintegral piece with the housing body and/or the base. The base, the atleast one bar, and the housing body can, for example, beinjection-molded in one integral piece from plastic, such aspolypropylene or ABS. The elastic bar, which connects the base to thehousing body, can make it easier to position the base in the aperture ofthe housing body when the elastic membrane is molded on. The elastic barcan also support the membrane, which can be particularly advantageouswith extensive membranes which otherwise tend to form creases or beexcessively yielding.

To obtain water-tightness of the housing in the region of the actuatingbutton, the base on which the actuating button sits can be constructedto be free of through-holes. The actuating button can partiallypenetrate the base such that no aperture extends all the way through thebase, from the outside of the base to the inside of the base.

In addition to enclosing the circumferential surface of the base, themembrane may at least partially cover the end faces of the base as ifthe base were cast integrally with the membrane. In some embodiments,however, at least the end face of the base facing the outer side of thehousing is constructed to be free of any overlay by the membrane. Themembrane can include a recess which is substantially the same size asthe end face of the base facing the outer side of the housing. In someembodiments, the base penetrates the membrane from its outer side to itsinner side. In such embodiments, the end face of the base facing theinner side of the housing is also constructed such that it is notoverlaid by the membrane.

The at least one elastic bar previously mentioned, which connects thebase to the housing body can be cast integrally with the membrane. Toobtain an attractive appearance, the at least one elastic bar can lie onthe inner side of the membrane. This configuration can be advantageousnot only for aesthetic reasons but also to provide a support for themembrane when the latter is depressed (e.g., depressed with a finger tipof the user).

For good visual and tactile recognition, the actuating button can beconstructed to be raised relative to the membrane.

In certain embodiments, the actuating button and the base are separatecomponents that are joined together, which enables them to be made ofdifferent materials. In some embodiments, the base is made of the samematerial as the housing body. The actuating button can be made of any ofvarious materials, such as metal, ceramic, glass, and/or plastic.

The actuating button and the base can be joined together in any ofvarious ways. In certain embodiments, the base has a blind-end borereceiving a shaft-shaped section of the actuating button. Theshaft-shaped section can be press-fitted in, adhesively bonded to, orcast integrally with the blind-end bore. To help prevent the actuatingbutton (e.g., the shaft-shaped section of the actuating button) fromdetaching itself from the blind-end bore, at least one radial rib and/orbead can be provided on the shaft. Such a radial projection digs intothe wall of the blind-end bore in the base, thereby decreasing (e.g.,preventing) the possibility of detachment.

To obtain a durable connection between the actuating button and thebase, it is also possible for the actuating button to be welded to thebase.

In some embodiments, the actuating button and the base can beconstructed to exhibit material homogeneity in one integral piece. Insuch embodiments, the base can form the actuating button.

It is generally beneficial, in particular when the actuating button issubsequently joined to the base and projects outwardly beyond thelatter, to prevent debris (e.g., dirt) from entering in between themembrane and the actuating button. Therefore, in some embodiments, themembrane includes an edge section that encloses the base and projectsbeyond the base towards the outer side of the appliance. The edgesection can abut with a precise fit (e.g., a press-fit) against an edgesection of the actuating button. When the actuating button is joined tothe base, the edge section of the membrane is deformed such that a pressfit is obtained between the actuating button and the membrane. In orderto prevent detachment of the membrane from the base as a result of thispressure, the base can have a radial projection (e.g., a circumferentialshoulder) on its end face facing the inside of the housing for seatingengagement with the membrane. When the actuating button is then placedon the base from the outside, thereby causing the edge section of themembrane to be compressed, the radial projection on the base absorbs thecorresponding pressure exerted on the membrane. The membrane is,therefore, compressed between the radial shoulder of the base and theradially projecting edge of the actuating button.

The edge section of the membrane, which projects toward the outside ofthe housing prior to mounting the actuating button, can form an annularcollar which engages the underside of the actuating button with its endface.

Alternatively, the edge section of the membrane around the base may forma boundary for a recess that is coaxial with and adjacent to the baseand into which the actuating button can be inserted with a precise fit.For snug seating of the actuating button on the membrane, the recess ofthe membrane as well as the underside of the actuating button can beshaped in a conical configuration. In certain embodiments, the recesshas a smaller cone angle than the cooperating underside of the actuatingbutton section.

In order to obtain an improved support of the membrane in cases where anextensive membrane is used, at least one protruding membrane supportmember, such as a wing, a thin plate, or the like, can be fastened(e.g., molded) onto the base and/or onto the at least one elastic bar.In some embodiments, the membrane is supported not only by the area ofthe elastic bar itself but also by the additional area provided by sucha protruding membrane support member. In certain embodiments, aprotruding plate or the corresponding wing can also be molded onto thebase or the membrane in order to achieve a special visual effect.

The base can also be connected by multiple elastic bars to the edge ofthe housing aperture. This can result in an improved support of themembrane.

In some embodiments, the material of the membrane can be convenientlybonded not only to the material of the base, which supports theactuating button, but also to the material of the housing body. Themembrane can, for example, be molded onto the edge of the correspondinghousing aperture using the two-component injection-molding method.

Other features and advantages are in the specification, the drawings,and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of the housing body of an electricalappliance housing, taken along the line A-A of FIG. 2, showing afragment of the housing body with an aperture and a base disposedtherein for fastening an actuating button.

FIG. 2 is a top plan view of the housing body and the aperture of FIG. 1provided therein.

FIG. 3 is a sectional view of the housing body similar to FIG. 1,showing the housing aperture sealed with an elastic membrane and anactuating button prior to its fastening to the base in the housingaperture.

FIG. 4 is a sectional view of the housing body similar to FIG. 3,showing the actuating button in joined condition.

FIG. 5 is a sectional view, similar to FIGS. 1, 3 and 4, of anelectrical appliance housing according to an alternative embodiment,showing the actuating button being joined to the base arranged in themembrane using a sonotrode.

FIG. 6 is a sectional view, similar to FIG. 3, of another embodiment ofan electrical appliance housing, showing a conical actuating buttonprior to being joined to the base arranged in the membrane.

FIG. 7 is a sectional view, similar to FIG. 4, of still anotherembodiment of an electrical appliance housing.

FIG. 8 is sectional view, similar to FIG. 7, of yet another embodimentof an electrical appliance housing.

FIG. 9 is a sectional view, similar to FIGS. 3 and 6, of an electricalappliance housing according to a further embodiment, showing theactuating button prior to being joined by friction welding to the basearranged in the membrane.

FIG. 10 is a sectional view of the electrical appliance housing of FIG.9, showing the actuating button joined to the base.

FIG. 11 is a sectional view, similar to the preceding Figures, ofanother embodiment, in which the actuating button is molded onto thebase using a two-component injection-molding process.

FIG. 12 is a sectional view, similar to the preceding Figures, of anelectrical appliance housing according to still another embodiment, inwhich the actuating button is constructed to exhibit materialhomogeneity with the base.

FIG. 13 is a sectional view, similar to FIG. 1, of a housing body of anelectrical appliance housing according to an embodiment, showing twobases for accommodating two actuating buttons in one housing aperture,the section being taken along the line B-B of FIG. 14.

FIG. 14 is a top plan view of the housing body of FIG. 13.

FIG. 15 is a sectional view, similar to FIGS. 1 and 13, of a housingbody of an electrical appliance housing, in which a base foraccommodating an actuating button in a housing aperture is integrallyformed on the housing body by two elastic bars, the section being takenalong the line C-C of FIG. 16.

FIG. 16 is a top plan view of the housing body of FIG. 15.

FIG. 17 is a top plan view, similar to FIG. 16, of a housing bodyaccording to another embodiment, showing a plate-shaped membrane supportmember integrally formed on the base.

FIG. 18 is a top plan view, similar to FIGS. 16 and 17, of a housingbody according to still another embodiment, showing multiple membranesupport members in the form of wings integrally formed on the base andbar in the housing aperture.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 to 4 are fragmentary views of a housing 1 of an electrictoothbrush or a similar electrical appliance including a housing body 2made from a hard plastic material, such as polypropylene or ABS, andhaving in its wall 3 an aperture 4 which in the embodiment shown has anapproximately rectangular circumference with radiused corners. It willbe understood, of course, that the aperture 4 may also be shaped inother forms.

Extending from the edge of the aperture 4 into the aperture 4 is a thinbar 5 which is a part of the housing body 2. As FIG. 1 shows, the bar 5is molded integrally with the wall 3. On its free end, the bar 5supports a base 6 which is aligned roughly central to the aperture 4 andin the embodiment shown has an approximately cylindrical contour. On itsend facing an inner side 7 of the electrical appliance housing 1 , thebase 6 has a radially projecting shoulder 8 (FIG. 1).

The bar 5, which extends parallel to the plane of the aperture 4, liesapproximately at the lower edge of the aperture 4 facing the inner side7.

The housing body 2, including the bar 5 and the base 6, and the aperture4 can be manufactured using injection molding techniques. In a secondinjection-molding operation, a membrane 9 can be injected into theaperture 4. The membrane 9 can be molded over the bar 5 and around thebase 6. As FIG. 3 shows, the membrane 9 has a projection 10 in the formof an annular collar extending circumferentially around the base 6. Themembrane 9 can be made of a soft plastic, such as TPE. During theinjection-molding operation this soft plastic material forms a bond withthe hard plastic material of the wall 3 of the housing body 2 and of thebar 5 and base 6 which are molded onto the housing body. The plasticmaterials of the housing body 2 including the bar 5 and the base 6 andthe material of the membrane 9 are compatible with each other, thusresulting in a firm bond. As FIG. 3 shows, the thickness of the membrane9 is smaller than the thickness of the wall 3. The surface of themembrane 9 facing an outer side 11 of the electrical appliance housing 1lies lower than the level of the wall 3 of the housing body 2surrounding the aperture 4. The housing body 2 thus has a slightdepression in the region of the aperture 4 sealed by the membrane 9.

An actuating button 12 of roughly mushroom shape is fastened to the base6. The actuating button 12 is comprised of a head 16 and a shaft-shapedneck 17 onto which a sharp-edged, radially projecting rib 18 is molded.The actuating button 12 can be made of any of various metals, such assteel, stainless steel, aluminum, and/or the like. Alternatively oradditionally, the actuating button 12 can be formed of any of variousother materials, such as a hard plastic, a ceramic, and/or a glass. Thesurface of the actuating button 12 can be finished using any of varioustechniques, such as electroplating, anodic oxidation, etching, coating,dyeing, grinding, blasting, and/or the like. Instead of having only onerib 18, it is also possible for multiple ribs to be arranged axially inseries on the shaft-shaped neck 17.

As FIGS. 3 and 4 show, the actuating button 12 can be cold-pressed intoa blind-end bore 19 constructed in the base 6. As a result, the rib 18can become anchored in the wall of the blind-end bore 19. Placing theactuating button 12 down onto the base 6 compresses the projection 10 ofthe membrane 9 between the shoulder 8 of the base 6 and the head 16 ofthe actuating button 12. The resulting press-fit can help to preventdirt from getting in between the membrane 9 and the head 16 of theactuating button 12.

To make it easier to press the neck 17 into the blind-end bore 19, theactuating button 12 can be heated prior to being pressed in. Inembodiments in which the actuating head 12 is made of metal, theactuating button 12 can be heated by induction in a high-frequencyelectric field.

Alternatively, it is also possible for the actuating button 12 to bepressed into the blind-end bore 19 of the base 6 using a sonotrode inthe form of a ram 20 vibrating at ultrasonic frequency, as shown in FIG.5. The ultrasonic vibration can be introduced into the actuating button12, causing the hard plastic of the base to be heated through frictionat the contact surface with the actuating button 12. This can make iteasier for the neck 17 and the rib 18 to enter the blind-end bore 19 andfor the plastic to flow into the annular space between the head 16, theneck 17, and the rib 18. After cooling, the actuating button 12 can besolidly connected to the base 6. As FIG. 5 shows, the membrane in thisembodiment has no bar-shaped projection around the base 6. Rather, themembrane includes a recess 21 whose contour corresponds to the head 16of the actuating button 12 and in which the head 16 sits with a precisefit after insertion of the button into the base 6.

In the embodiment of FIG. 5, both the head 16 of the actuating button 12and the recess 21 in the membrane 9 have a cylindrical contour.Alternatively, as shown in FIG. 6, the recess 21 in the membrane 9,which adjoins the base 6 axially toward the outer side, can be conicallyconstructed and can increase in diameter toward the outer side 11 at anangle a. The head 16 of the actuating button 12 can be shaped in aconical configuration. It decreases in diameter toward the neck 17 at anangle β, which can be larger than the angle a of the recess 21.Furthermore, the largest diameter D₂ of the head 16 is somewhat largerthan the corresponding diameter D₁ of the recess 21. After the actuatingbutton 12 is pressed in, the soft plastic of the membrane 9 in thevicinity of the head 16 is under tension, thus helping to prevent theingress of dirt into the recess 21.

As an alternative to the previously described embodiments, the neck 17of the actuating button 12 can be constructed with a smooth finish(e.g., free of projections). As FIG. 7 shows, the neck 17 sits with aprecise fit in the blind-end bore 19 of the base 6 and is bonded theretoby an adhesive. The recess 21 in the membrane matches the head 16 of theactuating button 12.

In a further variant of the actuating button 12 shown in FIG. 8, itsneck 17 supports an annular bead 22 instead of the previously describedsharp-edge rib 18. In this variant the actuating button 12 can be castintegrally with the base 6. The actuating button 12 can be inserted inthe injection mold such that hard plastic is molded around the neck 17and the bead 22 when the housing body 2 is injection-molded. In thesecond molding step, the soft plastic membrane 9 can then be molded onby the two-component injection method.

The actuating button 12 does not necessarily have a neck 17 adjoiningthe head 16. FIGS. 9 and 10 show an embodiment in which the actuatingbutton 12 is comprised of only the head 16, with its undersideconstructed to be flat. The base 6 is constructed to be somewhat raisedin relation to the membrane 9, thus enabling the actuating button 12 tobe joined to the base 6 by welding (e.g., by friction welding). The base6 and the actuating button 12 can be made from the same plastic or fromcompatible plastics, and both parts can be formed to have differentcolors. In embodiments in which the actuating button 12 is made of ABS,a decorative metal layer can be applied by electroplating to the visiblefaces prior to welding. As a comparison of FIGS. 9 and 10 shows, thebase 6 can be slightly abraded during friction welding to the actuatingbutton 12, resulting in the underside of the actuating button 12 restingflush on the upper side of the membrane 9 after the joining operation.

As FIG. 11 shows, the actuating button 12 can also be fastened to thebase 6 by the two-component injection-molding method. In this case, theactuating button 12 is made of hard plastic in order to obtain a firmbond in the injection-molding operation. In some embodiments, theplastic of the actuating button 12 is compatible with to (e.g., the sameas) the plastic of the base 6. Through the separate molding-on of theactuating button 12, the button 12 can be given a different color thanthe housing body 2, thus achieving good recognition. The membrane 9 canbe molded on in a third injection-molding operation.

The embodiment of FIG. 12 shows an actuating button 12 which is formedby the base 6 itself. In this embodiment the actuating button 12 isproduced as a continuation of the base 6 during the injection molding ofthe housing body 2. The membrane 9 is molded around the actuating button12 in the second injection-molding operation. In this embodiment thehousing body 2 and the actuating button 12 have the same color. However,recognition of the actuating button 12 can be very good when themembrane 9 has a different color. This version of the device can beparticularly inexpensive to manufacture.

As FIGS. 13 and 14 show, it is possible to arrange two bases 6 in theaperture 4 of the housing body 2, thus enabling two actuating buttons tobe fitted therein. As a result, several function elements lyingunderneath the membrane can be actuated. It is also possible for aswitch lying underneath to be switched on with the one actuating buttonand for the same switch to be switched off with the other actuatingbutton. As FIGS. 13 and 14 show, the two bases 6 are each arranged on aseparate bar 5, each of which extends from the wall 3 of the housingbody 2 into the aperture 4. Independent actuation of the actuatingbuttons fastened to the two bases 6 is thus possible, regardless of theinfluence of the membrane 9.

According to another embodiment, the base 6 can be supported in theaperture 4 by two bars 5. As FIGS. 15 and 16 show, the two flat bars,which are arranged in a common plane parallel to the plane of theaperture 4, are shaped in an arcuate or undulating configuration inorder to reduce (e.g., minimize) the bending resistance in a directiontransverse to their plane. They extend to opposite lying edges of theaperture 4. After a membrane is molded around the bars 5 and the base 6,the base 6 can receive an actuating button in the way previouslydescribed.

An extensive membrane 9 may be provided in the housing body 2 foraesthetic reasons. There may, however, be a risk of the membrane 9becoming deformed and forming bulges or creases for example. To remedythis, a membrane support member 23 protruding parallel to the plane ofthe aperture 4 can be molded onto the bar 5 and/or the base 6. As FIG.17 shows, a membrane support member 23 in the form of a thin plate canbe fastened to the base 6 and the bar 5 with the plate being arrangedroughly concentric to the aperture 4. As shown in FIG. 18, it is alsopossible to provide multiple membrane support members 23 in the form offingers or wings which extend in the plane of the aperture 4 away fromthe base 6 and transverse to the bar 5. After a membrane of soft plasticis molded around the bars 5, the base 6, and the membrane supportmembers 23, the base 6 can receive an actuating button in the mannerpreviously described.

In the previously described embodiments the actuating button 12including the head 16, the neck 17, and the rib 18 or bead 22 weredescribed as being constructed with a round cross section. However, itis also possible to provide a non-round cross section in order to anchorthe actuating button 12 in the base 6 in a manner preventing relativerotation. In this arrangement a direction symbol such as an arrow can beprovided on the actuating button 12 to indicate the pushing directionand/or the effect of actuating the actuating button 12.

In the previously described embodiments the wall 3 of the housing body 2as well as the membrane 9 were described as being of essentially flatconstruction. It will be understood, of course, that curved walls ormembranes can alternatively or additionally be provided.

Other embodiments are in the claims.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests ordiscloses any such invention. Further, to the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

1. An electrical appliance housing, comprising: a hard plastic housingbody having a wall with an aperture, the housing body having at leastone integrally molded bar extending into the aperture, the at least oneintegrally molded bar having a free end supporting a base, wherein theat least one integrally molded bar extends generally parallel to a planeof the aperture; a soft plastic membrane enclosing a circumferentialsurface of the base and at least partially covering a pair of end facesof the base, wherein the hard plastic base is bonded to the membrane sono water can reach an interior of the housing and the at least oneintegrally molded bar supports the membrane; and an actuator buttonfastened to the base, the actuator button and the base are separatecomponents that are joined together, wherein the actuating buttonprotrudes beyond the membrane towards an outer side of the housing body.2. The electrical appliance housing of claim 1 wherein a surface of themembrane facing an outer side of the housing body lies lower than alevel of the wall of the housing body surrounding the aperture.
 3. Theelectrical appliance housing of claim 1 wherein the base has a radiallyprojecting shoulder.
 4. The electrical appliance housing of claim 1wherein the base is aligned roughly central to the aperture.
 5. Theelectrical appliance housing of claim 1 wherein the membrane is bondedto the housing body.
 6. The electrical appliance housing of claim 1wherein the membrane projecting toward an outside of the housing has anannular collar engaging the actuator button.
 7. The electrical appliancehousing of claim 1 wherein the actuator button is raised relative to themembrane.
 8. The electrical appliance housing of claim 1, wherein themembrane is directly bonded to the base and the at least one bar.
 9. Theelectrical appliance housing of claim 1, wherein the membrane includesan edge section that encloses the base and projects beyond the basetowards an outer side of the housing body.
 10. The electrical appliancehousing of claim 1, wherein the membrane defines a recess, at least anouter side of the base penetrating the membrane through the recess. 11.The electrical appliance housing of claim 1, wherein the base receives aneck of the actuating button.
 12. The electrical appliance housing ofclaim 1, wherein the actuating button is positioned on the membrane. 13.The electrical appliance housing of claim 1, wherein the actuatingbutton is positioned in the membrane.
 14. The electrical appliancehousing of claim 1, wherein the at least one integrally molded bar isintegrally molded with the base.
 15. The electrical appliance housing ofclaim 1, wherein the at least one integrally molded bar extendsapproximately at a lower edge of the aperture.
 16. The electricalappliance housing of claim 1, wherein the at least one integrally moldedbar comprises two bars, the two bars arranged in a common plane parallelto a plane of the aperture.
 17. The electrical appliance housing ofclaim 16, wherein each of the two bars extends to opposite edges of theaperture.
 18. The electrical appliance housing of claim 16, wherein thetwo bars is configured to reduce the bending resistance in a directiontransverse to a common plane.
 19. The electrical appliance housing ofclaim 16, wherein each the two bars is shaped in an undulatingconfiguration.
 20. The electrical appliance housing of claim 16, whereinthe two bars are integrally molded with the base.